This invention is generally directed to layered photoresponsive imaging members, and more specifically to photoconductive members having incorporated therein certain pyranthrone compounds. In one embodiment of the present invention, there are provided organic photoconductive layered imaging members comprised of certain pyranthrone compounds and aryl amine hole transport layers. Further, in one important embodiment of the present invention there is provided a photoresponsive imaging member or device comprised of pyranthrones selected from tribromo-8,16-pyranthrenedione (Paliogen Red L3530), and trichloro-8,16-pyranthrenedione (Paliogen Orange L2640), and the derivatives thereof; and an aryl amine hole transport layer. The aforementioned photoconductive members possess a number of advantages indicated hereinafter inclusive of high photosensitivity, low residual potentials, low dark decay characteristics, stable cycling properties; and are easily sublimable. Accordingly, the photoresponsive imaging members of the present invention can be selected for various electrophotographic imaging and printing processes wherein, for example, latent images are formed thereon followed by development and transfer to a suitable substrate.
Illustrated in U.S. Pat. No. 4,315,981 are organic double layered electrophotographic recording materials consisting of an electroconductive support with a photoconductive double layer of organic materials, which consist of a homogeneous opaque charge carrier producing dyestuff layer obtained from a more annealed quinone, or the substitution product thereof selected from the group consisting of dibenzopylene, quinone, anthraquinone, pyranthrone, dibenzathrone, and flaventhrone, and a transparent top layer of insulating materials of at least one charge transporting compound, which transport layer consists of a charge transporting monomer, reference for example column 2, lines 37 to 56. Further, as indicated in column 4, lines 1 to 22, as the formula 9 compound for the imaging member of '981 there can be selected dibromo-8,16-pyranthrenedione (Indanthrene Orange RRTS, C.I. 59,705). Moreover, it is stated in column 4, begining at around line 53, that the organic dyestuff layer may be applied by vapor depositing the dyestuff in a vacuum. Also, this patent discloses a number of resinous binders for the charge transport layer including polycarbonate resins, reference column 7. Further, in U.S. Pat. No. 3,871,882 there are disclosed layered electrophotographic recording materials containing an electroconductive support material and a photoconductive double layer of organic materials, reference for example the Abstract of the Disclosure. Other representative patents of background interest include U.S. Pat. Nos. 3,871,882 and 3,973,959.
Furthermore, in Konishiroku Kokai Japanese 59/184349/A2[84/184349], 19 Oct. 1984, there is disclosed the use of selected pyranthrones as charge generator layers in conjunction with hydrazone charge transport layers. Specifically, a solution coated dispersion of dibromo-8,16-pyranthrenedione in a polymer binder can be selected as the charge generator layer. Also, in U.S. Pat. No. 3,877,935 there are disclosed imaging members with dibromo-8,16-pyranthrenedione vacuum coated charge generator layers contiguous with poly(vinyl carbazole) charge transport layers.
Additionally, numerous different xerographic photoconductive members are known including, for example, a homogenerous layer of a single material such as vitreous selenium, or a composite layered device containing a dispersion of a photoconductive composition. An example of one type of composite xerographic photoconductive member is described, for example, in U.S. Pat. No. 3,121,006 wherein there is disclosed finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. These members contain, for example, coated on a paper backing a binder layer containing particles of zinc oxide uniformly dispersed therein. The binder materials disclosed in this patent comprise a material such as polycarbonate resins, polyester resins, polyamide resins, and the like, which are incapable of transporting for any significant distance injected charge carriers generated by the photoconductive particles. Accordingly, as a result the photoconductive particles must be in a substantially contiguous particle to particle contact throughout the layer for the purpose of permitting charge dissipation required for a cyclic operation.
There are also known photoreceptor materials comprised of inorganic or organic materials wherein the charge carrier generating, and charge carrier transport functions are accomplished by discrete contiguous layers. Additionally, layered photoreceptor materials are disclosed in the prior art which include an overcoating layer of an electrically insulating polymeric material. However, the art of xerography continues to advance and more stringent demands need to be met by the copying apparatus in order to increase performance standards, and to obtain quality images.
Also, there have been disclosed other layered photoresponsive devices including those comprised of separate generating layers, and transport layers as described in U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference. Examples of photogenerating layers disclosed in this patent include trigonal selenium and phthalocyanines, while examples of transport layers include certain diamines as mentioned herein.
Many other patents are in existence describing photoresponsive devices including layered devices containing generating substances, such as U.S. Pat. No. 3,041,167 which discloses an overcoated imaging member containing a conductive substrate, a photoconductive layer, and an overcoating layer of an electrically insulating polymeric material. This member is utilized in an electrophotographic copying system by, for example, initially charging the member with an electrostatic charge of a first polarity, and imagewise exposing to form an electrostatic latent image, which can be subsequently developed to form a visible image.
Furthermore, there are disclosed in U.S. Pat. Nos. 4,232,102 and 4,233,383 photoresponsive imaging members comprised of trigonal selenium doped with sodium carbonate, sodium selenite, and trigonal selenium doped with barium carbonate, and barium selenite, or mixtures thereof. Moreover, there are disclosed in U.S. Pat. No. 3,824,099 certain photosensitive hydroxy squaraine compositions. According to the disclosure of this patent, the squaraine compositions are photosensitive in normal electrostatographic imaging systems.
In U.S. Pat. No. 4,508,803, the disclosure of which is totally incorporated herein by reference, there is described an improved photoresponsive device comprised of a supporting substrate, a hole blocking layer, an optional adhesive interface layer, an inorganic photogenerating layer, a photoconducting composition layer comprised of benzyl fluorinated squaraine compositions, and a hole transport layer. Other representative patents disclosing photoconductive devices with squaraine components therein, or processes for the preparation of squaraines include U.S. Pat. Nos. 4,507,408; 4,552,822; 4,559,286; 4,507,480; 4,524,220; 4,524,219; 4,524,218; 4,525,592; 4,559,286; 4,415,639; 4,471,041; and 4,486,520. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
Moreover, disclosed in the prior art are composite electrophotographic photosensitive materials with various azo compounds. For example, there is illustrated in Japanese Ricoh Patent Publication 6064354, published April 12, 1985, composite photoconductors wherein one of the photoconductor layers contain an azo compound of the formulas as illustrated. Further, there are illustrated in several U.S. patents and publications layered organic electrophotographic photoconductor elements with azo, bisazo, or related compounds. Examples of these patents and publications include U.S. Pat. Nos. 4,400,455; 4,551,404; 4,390,608; 4,327,168; 4,299,896; 4,314,015; 4,486,522; 4,486,519; and 4,551,404; and Konishiroku Japanese Patent Laid Open Publication 60111247.
Although photoconductive imaging members are known, there remains a need for members with other photogenerator layers. Additionally, there continues to be a need for layered photoresponsive imaging members having incorporated therein certain pyranthrone compounds, which members will enable the generation of acceptable high quality images and wherein these members can be repeatedly used in a number of imaging cycles without deterioration thereof from the machine environment or surrounding conditions. Moreover, there is a need for improved layered photoresponsive imaging members wherein the pyranthrone compounds selected for one of the layers in combination with specific aryl amine charge transport compositions are substantially inert to the users of such members. Additionally, there is an important need for layered photoconductors with pyranthrone compounds, which photoconductors are of high sensitivity, have low dark decay values, low residual potentials, and possess high cyclic stability. Furthermore, there continues to be a need for photoresponsive imaging members which can be positively or negatively charged thus permitting the development of images, including color images, with positively or negatively charged toner compositions. Moreover, there continues to be an important need for disposable imaging members with nontoxic organic pigments. Also, there is a need for disposable imaging members useful in xerographic imaging processes, and xerographic printing systems wherein, for example, light emitting diodes (LED), helium cadmium or helium-neon lasers can be selected; and wherein these members are particularly sensitive to the visible region of the spectrum, that is from about 400 to about 700 nanometers. Also, there is a need for low cost, high quality imaging members wherein reduced amounts of photosensitive materials can be selected.